Some of the tenants have been very inconsiderate in discarding their garbage on the back stairway and blocking the fire exits.

inconsiderate 是由前缀 in-（表示"不、非"）和 considerate（考虑周到的）组成的形容词。considerate 来自动词 consider（考虑），加上后缀 -ate 构成形容词。inconsiderate 的字面意思是"不考虑他人的"，指"不体谅别人的、自私的"。